EP0159082B1 - Process for treating wool - Google Patents

Description

• un prélavage,
• une acidification,
• une élimination d'un excès d'acide et
• une carbonisation.

The present invention relates to a method of treating wool according to which the wool is subjected successively to

• a prewash,
• acidification,
• elimination of excess acid and
• charring.

Known methods of this kind include carbonization in an aqueous medium. In fact, according to these known processes, the acidification is carried out by means of an acidified aqueous solution and the excess acid is removed by spinning. Despite this spinning, the water retention of the wool is still significant.

The carbonization is therefore of a fairly long duration; it can alter wool fibers and cause felting.

The object of the invention is to remedy these drawbacks and to provide a rapid and economical treatment process giving treated wool of improved quality.

• on réalise l'acidification à l'aide d'un solvant alcoolique en solution aqueuse acidifiée et
• on réalise l'élimination de l'excès d'acide à un solvant hydrocarboné, la carbonisation s'effectuant ainsi en milieu solvant.

For this purpose

• acidification is carried out using an alcoholic solvent in an acidified aqueous solution and
• the excess acid is removed from a hydrocarbon solvent, carbonization being carried out in a solvent medium.

Carbonization takes place at a higher temperature and can therefore have a short duration, even less than two minutes.

In a preferred embodiment of the invention, the prewash, the acidification, the said elimination of the excess acid and the carbonization of the wool are carried out while the latter is moving with the same perforated conveyor belt.

In a particular embodiment of the invention, carbonization is carried out by circulating the wool with a conveyor belt in several compartments and by circulating an inert gas at a temperature of the order of 120 ° C to 140 ° C against -current through these compartments.

Other details and particularities of the invention will emerge from the description of a wool treatment process according to the invention and of an installation for the implementation of this process, given below by way of example not limiting and with reference to the attached drawing.

The figure is a schematic view of an installation for implementing the wool treatment method according to the invention.

The installation according to the figure comprises a perforated endless conveyor belt 1 supported by two drums 2, one drum of which drives the belt. The direction of movement of the upper strand of the conveyor 1 is indicated by the arrow 3.

Wool is admitted in 4 in a layer on the upper strand of carpet 1.

This wool successively passes through an entry airlock 5, a prewash part 6 where it is treated with a hydrocarbon solvent, an acidification part 7, where it is treated with an alcoholic solvent in acidified aqueous solution, an elimination part excess acid 8 where it is treated again with a hydrocarbon solvent, a transfer airlock 9, a carbonizer 10 and an evacuation airlock 11.

These parts 5 to 11 of the installation are mounted in line and crossed by the belt 1.

The prewash part 6 comprises three sections 12-13, 14-15 and 16-17, the acidification part 7 comprises two sections 18-19 and 20-21 and the excess acid removal part 8 includes a section 22-23.

Each section includes a watering chamber 12, 14, 16, 18, 20 or 22, through which a part of the upper strand of the carpet 1 passes and the funnel bottom of which is provided with a discharge opening 24 leading to a decanter 13, 15, 17, 19, 21 or 23.

Each section also includes a sprinkler device consisting of a number of sprinkler heads 25, a supply line 26 connecting the sprinkler device of the section to the upper part of its decanter and a pump 27 mounted in the pipe 26. On the discharge side of each chamber 12, 14, 16, 18, 20 and 22 are mounted two compression rollers 28 between which pass the upper strand of the carpet 1 and the layer of wool which it carries.

The sprinkler heads 25 are mounted above the wool layer but the chambers 14, 20 and 22 also include a sprinkler head directed towards the underside of the upper strand of the carpet 1.

The pumps 27 discharge a hydrocarbon solvent under pressure to the sprinklers of the chambers 12, 14 and 16 of the prewash part 6, an alcoholic solvent in acidified aqueous solution under low pressure to the sprinklers of the chambers 18 and 20 of the acidification part 7 and a hydrocarbon solvent under adjustable pressure to the sprinklers of the chamber 22 of the excess acid elimination part 8.

Hydrocarbon solvent is introduced at 49 into chamber 22 of the excess acid removal part 8.

To this solvent is added the recycled solvent and watered under adjustable pressure by the sprinkler heads 25 of this part. The solvent causes the excess acid and is collected in the decanter 23 where it forms the lower phase. This lower phase is sent via line 29 to the previous acidification section 20-21; to this end, the pipe 29 opens into the supply pipe 26 of section 20-21.

The upper phase of the decanter 23, comprising the hydrocarbon solvent, is allowed to overflow towards the upper part of the decanter 17, as indicated by the arrow 30 in the figure.

The decanter 17 is allowed to overflow towards the decanter 15 and the latter towards the decanter 13, as indicated by the arrows 31 in the figure. The hydrocarbon solvent therefore goes upstream against the prewash part 6, taking charge progressively with grease.

Watering with a hydrocarbon solvent in the excess acid removal part 8 has in particular the effect of spinning the wool after acidification in traditional methods, but takes only a few seconds and requires no manipulation. complementary to wool.

As the hydrocarbon solvent, hexane can be used efficiently and advantageously.

An aqueous alcoholic solution is introduced at 50 into the watering chamber 20 of the last section of the acidification part 7 and sulfuric acid is added thereto separately by automatic dosing. Preferably 5 to 10% of concentrated sulfuric acid is added relative to the added amount of alcoholic solution. As alcohol, isopropyl alcohol is used, for example. The decanter 21 of the last section of the acidification part 7 is made to project towards the upper part of the decanter 19 of the first section of this part, as indicated by the arrow 32 in the figure.

The acidification of vegetable matter. Naked in wool is done very quickly, thanks to the very high wettability of the latter by the acid solution, due to the presence of alcohol at average concentrations.

The overflow of the decanter 19 feeds the upper part of the decanter 13 of the first section of the prewash part 6, as indicated by the arrow 33 in the figure. In this decanter 13 the alcoholic solution is mixed with the miscella spraying the wool in the chamber 12.

Is added to the upper phase of the decanter 13 also a portion of alcoholic solution supplied by a line 34 which is supplied by the overflow of a complementary decanter 35 described below.

The prewash is therefore done with the same hydrocarbon solvent as the removal of the excess acid and only using recycled hydrocarbon solvent. This prewash is done in two stages, first using miscella and alcoholic solution in chamber 12 of the first section and using miscella alone in chambers 14 and 16 of the other two sections of the part pre-wash 6. During this pre-wash the wool grease is dissolved and the insoluble impurities, soil and sand, are mechanically entrained.

Insoluble impurities are deposited in the decanters 13, 15, 17, 19 and 21. They are eliminated towards a degreasing device 37 mounted below the decanters. These insoluble impurities are transported using a transport screw to the end of the device situated on the side of the excess acid removal part 8 and these impurities are washed against the current by the same hydrocarbon solvent with which the excess acid removal part 8 is fed. This hydrocarbon solvent is introduced via line 38 into device 37.

The miscella obtained after degreasing the insoluble impurities in the device 37 and the fat solution overflowing from the first settling tank 13 and comprising from 15 to 20% of fat, are pumped by a circulation pump 40 through the pipe 39 to a unit 41 where the solution is deacidified by washing with an aqueous alcoholic solution. The deacidified solution is sent, possibly after refining in a refining unit, to a distillation unit not shown in the figure where the wool fat is recovered.

The alcoholic solution can be returned after extraction of the acid to the acidification part 7.

The sludge drained from the decanters 13, 15. 17, 19 and 21, collected and degreased in the device 37, are sent by the pump 42 through the line 43 to the complementary decanter 35. As already mentioned, the upper phase of this decanter 35 on the first prewash section. The sludge from this decanter 35 is collected which has a solid matter concentration close to 30% and it is pumped using the circulation pump 44 through line 45 to a neutralization unit not shown in the figure. After neutralization, this sludge can be distilled in order to recover the alcohol. The sludge is then found in a concentrated aqueous solution at 60%, with a minimum consumption of steam. This sludge has a fertilizing value and can be used as fertilizer, either as it is or after drying.

After acidification and elimination of the excess acid, the wool still deposited on the conveyor belt 1 is made to penetrate via the transfer airlock 9 into the carbonizer 10. This carbonizer 10 is divided into a series of sections 46 in which fans 47 blow an inert gas heated to 120 ° C to 140 ° C through the layer of wool to carbonize the vegetable matter impregnated with acid.

For safety reasons, given the presence of solvents, air is used as gas which has been rid of its oxygen by combustion.

This gas is introduced via line 48 in the last section 46. This gas rises up the carbonizer against the current while taking charge of solvents. The acid contained in plants is thus concentrated.

The gas from the first section 46 is discharged and this gas is treated in an annex unit, not shown in the figure, where the solvents are recovered.

Since, thanks to the presence of solvents, the water retention of the wool after acidification is reduced, a rise in temperature and very rapid carbonization are possible. Because of the compression rollers 28 in the excess acid removal part 8, the retention of solvents is ultimately less than 50%.

Carbonization can be completed in less than two minutes at temperatures between 120 ° C and 140 ° C and solvents can simultaneously be recovered by methodical extraction against the current by an inert gas.

The number of sections of the carbonizer depends on the desired capacity and the plant content of the wool.

The wool leaving the carbonizer 10 is discharged from the conveyor belt 1 via the evacuation hatch 11.

This wool is sent to conventional grinding and dusting installations. Then the wool can be deacidified, either with water on a conventional line with four or five baths, or using aqueous alcoholic rinsing and neutralization solutions on a line with a perforated conveyor belt.

In the latter case, a final rinsing with hydrocarbon solvent added with a slight amount of wool grease from the prewash is added to the neutralization. The purpose of this additional treatment, divided into one or two sprinkling sections, is to improve the dedusting of carbonized wool, to reduce the water and alcoholic solvent content before drying and to reload the wool fiber with a content in sufficient fat to facilitate the following operations, such as carding.

The process described above is particularly indicated for treating wools with a high vegetable content.

Prewash, acidification and carbonization are carried out together on a single treatment line in less than three minutes.

The exceptional speed of the process is due to the very high efficiency of the extraction of fat and soluble impurities, to the very rapid acidification of plant materials thanks to the presence of alcohol at medium concentrations, to the elimination of the excess acid with the help of a sprinkling of a hydrocarbon solvent, and the rapidity of carbonization thanks to the water retention of the very reduced wool.

The carbonization being carried out in a solvent medium the wool fibers are much less altered after carbonization and the felting is reduced. This results in a higher carded ribbon yield. This is due to the fact that the prewash is carried out cold without the intervention of water, that the acidification is carried out in an alcohol medium for a limited period and at acid concentrations lower than the concentrations normally used in known processes, than removal of the excess acid is done in a simple and efficient way, that the carbonization is done in an extremely fast way and that during the whole process no mechanical stirring of the wool takes place.

All of the by-products are recovered and the solvents used are recycled after recovery of the by-products. Since there are no releases, no pollution is caused.

Despite the complete recovery of the by-products, the steam consumption is reduced and lower than that of the known traditional processes and the water consumption is also very low, that is to say less than 1 kg / kg of treated material .

More than 95% of the fat extracted can be recovered, either as it is, or in the form of anhydrous refined lanolin or its derivatives.

The length of the processing line is less than the lines used to carry out the known methods.

The prewash section does not necessarily have to have three sections. The number of sections depends on the washed performance of the wool and in particular on its fat content.

The acidification part does not necessarily have to have two sections. The number of sections in this part depends on the plant content of the wool.

Claims (14)

1. Process for treating wool, according to which one subjects the wool succeedingly to

a pre-washing,

an acidifying,

an excess acid removal, and

a carbonisation,

characterized in that

one performs the acidifying by means of an alcoholic solvent in acidified aqueous solution and

one performs the excess acid removal with an hydrocarbonated solvent, the carbonisation thus being performed in solvent medium.

2. Process according to the preceding claim, characterized in that use is made of hexane as hydrocarbonated solvent.

3. Process according to either one of the preceding claims, characterized in that acidifying is performed by means of an alcoholic solvent in aqueous solution acidified with sulfuric acid in a concentration from 5 to 10 %.

4. Process according to any one of the preceding claims, characterised in that one performs the pre-washing by means of the hydrocarbonated solvent.

5. Process according to any one of the preceding claims, characterised in that one performs the pre-washing, the acidifying, said excess acid removal and the carbonisation of the wool while said latter wool is moved by one and the same perforated conveying belt.

6. Process according to the preceding claim, characterized in that each of said steps of the pre-washing, acidifying and removal is being performed in at least one section comprising at least one sprinkling device above the belt and at least one decanting device underneath said belt, and in that part at least of the top phase being formed in the decanting device, is cycled back to the corresponding sprinkling device.

7. Process according to the preceding claim, characterized in that upstream of each sprinkling device, the wool is pressed and the thus-released liquid is collected in the section decanting device.

8. Process according to any one of the preceding claims, characterised in that the sludges settling down in those sections preceding the excess acid removal, are degreased by conveying same in counter-flow with hydrocarbonated solvent.

9. Process according to claims 4, 6 and 8, characterized in that use is made of the same hydrocarbonated solvent for pre-washing and excess acid removal, one adds hydrocarbonated solvent in the excess acid removal section, one leads the bottom phase being formed in this section and comprising the carried-away excess acid to the preceding acidifying section, one feeds the top phase being formed in said same section partly to the sprinkling device of this same section, and partly through an overflow, to the pre-washing section.

10. Process according to the preceding claim, characterized in that as well the pre-washing as the acidifying is performed in a plurality of sections, alcoholic solvent is added as acidified aqueous solution to the last section in the acidifying part, the top phase being formed in the decanting devices from the acidifying part sections is fed by overflow to a previous decanting device from said same acidifying part, to the exception of that top phase being formed in the decanting device from the acidifying part first section which is fed to the pre-washing part first section, where the pre-washing is thus performed by means of a mixture of micella and alcoholic solution, and the top phase being formed in the decanting device from the excess acid removal part section is fed to the last section in the pre-washing part where the pre-washing is thus performed by means of micella.

11. Process according to claim 8, characterized in that the degreased sludges are fed to an additional decanting device where an alcoholic solution is recovered, which is led to the first section of the pre-washing part.

12. Process according to the preceding claim, characterized in that the sludges from the additional decanting device are neutralized and the alcohol is recovered therefrom by distillation.

13. Process according to any one of the preceding claims, characterised in that the carbonisation is performed by passing the wool with a conveying belt through a plurality of compartments, and by flowing an inert gas at a temperature in the range from 120 °C to 140 °C in counter-flow through said compartments.

14. Process according to any one of the preceding claims, characterized in that the wool is subjected after the carbonisation, to a desacidify- ing operation by means of an aqueous alcoholic solution, and to a rinsing with a grease-enriched hydrocarbonated solvent.

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